Circular-knitting machine



May 15', 1923. 1,455,370

R. W. WALTON CIRCULAR KNITTING MACHINE Filed Sept. 17. 1921 M/VE/VTORPatented wit- 15, was.

ROBERT W. WALTON, 0F PHILADELPHIA, PENNSYLVANIA.

CIRCULAR-KNITTING MACHINE.

Application filed September 17, 1921. Serial No. 501,316.

T 0 all whom it may concern:

Be it known that I, ROBERT V. lVAL'roN, a citizen of the United States,residing at Philadelphia, county of Philadelphia, and State ofPennsylvania, have invented a new and useful Improvement inCircular-Knitting Machines, of which the following is a full, clear, andexact description, reference being had to the accompanying drawings,which form a part of this specification.

My invention relates to circular knitting machines, more especiallythose knitting continuous tubular fabric in the manufacture of hosiery.This tubular fabric is afterwards cut into lengths, upon which footportions are knitted, and it is common practice to knit what is termed aloose course near the end of each of said lengths for the followingreason.

After being cut into lengths, as described, each piece is mounted byhand on a transfer ring. This ring comprises a circle of points equal innumber to the needles in the circular knitting head and one end of eachpiece is pressed onto this ring so that one of the points projectsthrough each individual loop in one of the courses of the tubular fabricnear the end of the piece. This is called the topping operation. Thering is then inverted over the knitting head of a machine for knittingthe foot portion and the loops are transferred from the points to theneedles of the machine whereby everything is in readiness for theoperation of knitting the foot onto the length of tubular fabric.

Therefore, after a certain length of regular tubular fabric has beenknitted, the machine is set to automatically knit a course of elongatedstitches wherein the yarn is pulled out to a greater length by theneedles for the pur ose of facilitating the topping operation. owever.it is found in practice that the knitting of this loose course is veryapt to produce drop stitches, necessitating a mending operation beforethe piece is ready for topping, adding appreciably to the time and costof production. It is to obviate this difficulty that my invention isdesigned.

It is customary to knit the stocking fabric with two threads of yarn. Inthe process of knitting, one of these threads is bound to be in greatertension than the other, with i the result that in the'loose course thetighter needles below their regular knitting depth and at the same pointa cam is introduced beneath the dial needles for raising them up, thuslengthening the distance between the heads of both sets of needles justat the point where the yarn is fed in and therefore drawing longerloops.

, Drawing the longer loops tends to pull up on the cylinder needles withthe result that directly their butts have passed thelowest point of thedepressed knitting cam, they are at once raised up to the guard cam.This immediate raising of thecylinder needles, together with thelowering of the dial needles to their regular level directly they havepassed the cam at the knitting point, produces such a slack in thefabric between the needles that many stitches are dropped.

In my invention I provide means for lowering the guard cam justfollowing the lowering of the main stitch cam with the result that whenthe cylinder needles pass the lowest point of the stitch cam they arenot allowed to be drawn up as heretofore, but their butts, striking thislower guard cam, are deflected gradually to their normal level, and theloops on the needles are not allowed to become so slack as to fly offand form drop stitches.

Having now described in general terms the object of my invention, thenecessity for and value of which will be readily understood andappreciated by those skilled in the art, I will proceed with a detaileddescription of mechanism employed in lowering the guard cam as describedin connection with the accompanying drawings, in which,

Fig. 1 is a diagrammatic showing of a section of fabric showing a loosecourse.

Fig. 1 is a similar view showing dropped stitches.

Fig. 2 is a cross-section through one side of the knitting head of themachine, showing the dial and circular needles at the knittin point.

ig. 3 is a plan view of a portion of the cam ring embodying myinvention.

Fig. 4 is a developed front view of the mechanism shown in Fig. 3.

Fig. 5 is a rear or outside view of the mechanism shown in Fig. 3.

The cylinder stitch cam' a is secured to post I) which is verticallyslidable through the top 0 of the cam ring, and normally pressed upwardby a spring not shown, as is old and well known in the art. Post 6carries a head d, in the form of a cam plate, which is adapted to beactuated by set screws 6 in an arm f secured to a pivot post 9 mountedin the cam ring. An adjusting screw t, which overhangs the edge of plated, limits the upward movement of the knitting cam. A clamp h is mountedon the set .screws and carries a cam 71 for acting on the dial needlesj. Pivot post 9 carries an arm which projects beyond the cam ring and isactuable by well known means to turn the pivot post'and with it arm f.

I have mounted the guard cam m on a post 7, vertically slidable throughtop 0 of the cam ring and normally held up by spring 0 so the cam isagainst under side of top 0, as indicated in broken lines in Fig. 4. Fordepressing the guard cam, I provide a twopiece block 1) clamped to setscrews 9 screwed into arm 7 in such a position that a beveled portion 1of the block will act upon the similarly beveled top of post n, in theinward turning of arm 7, to depress said post. By loosening the clamp ofblock p and screwing set screws 9, the block may be adjusted to givepost n and guard cam m the downward movement required.

Normally arm f is turned outwardly so its set screws 6 are out of actionwith regard to cam plate d. When a loose course is to be knit, ashereinbefore described, arm is is actuated to turn arm 7 inwardly untilset screws e contact with and override plate d, pressing it downward andwith it the knitting cam a to lower the cylinder needles 8. At the sametime cam '5 acts to raise the dial needles 9' and lengthen the pull ofthe yarn between the two sets of needles. While the knitting cam a isbeing depressed by set screws 0 moving on the cam face of plate (2, thebeveled corner 1 of block 17 contacts with post 71 and starts to depressit and with it the guard cam m. When arm 7 completes its inward turn,both cams a and marrive at their lower position and remain so until theloose course is completed when arm f is withdrawn and they again rise totheir normal knitting osition.

This metho of action, whereby the stitch cam leads in the downwardmovement and is followed by the guard cam, is newssary in order not toput an extra'strain on the loops formed just before the cam was lowered,which would be stretched and broken if the two cams actedsimultaneously.

In the knitted fabric indicated in the diagrams, Figs 1 and 1 the twostrands of yarn should always act together as if they were a singlethread. A perfect loop in the loose course is thus indicated at m, and 3indicates drop stitches of one of the strands, the tighter thread beingheld on the needles and knitted, as previously described. It will beunderstood that when knitting with a single strand, the thread is liableto be thrown off the needles on the loose course in a similar manner, sothat my invention applies equally for use in knitting with single ordouble threads.

The advantages of my invention result from the provision of means formaintaining the cylinder needles depressed for a. short distance beyondthe low point of the stitch cam for the circular needles and therebymaintain the newly formed loops under tension, which will prevent thedropping of stitches. By maintaining the I c linder needles depressedfor a short time a ter the loops have been formed, I am not only enabledto form a loose course without danger of dropping stitches, but amenabled to form a very much looser course than heretofore, which is verydesirable to facilitate transferring, and at the same time I am enabledto make a loose course having very long stitches without lowering thestitch cam a great extent. This I am enabled to do as the needles, asthey pass under the stitch cam, draw the yarn from the yarn supply onlyand not from the yarn supply and the newly formed loops on the needles,which have just passed under the stitch cam.

By depressing the guard cam a short time after depressing the stitchcam, I avoid all danger of straining the short s formed on the cylinderneedles just prior to the lowering of the stitch cam.

The two cams are arranged to reach their lowest position and act uponthe needles at substantially the same relative time-relative as regardsthe needles. That is, by the time the first needles passing under thelowered stitch cam reach the guard cam, it alllso is in loweredposition, then and not till t en.

The lag of the ard cam is equivalent to the time it takes t e needles topass from the low point of one cam to the lowpoint of the other. Thisallows the needles to be thrown off, and does not unduly strain the lastpreceding short loops as the guard cam curves off from this pointallowin the needles to rise, and also those last few 5 ort loops drawsome thread from th first long ones.

Similarly, at the end of the loose course, the stitch cam leads in therising movement by just the time it takes the last long 100 needle toreach the low point of the guar cam. Then and. not till then does theguard cam rise, which serves to keep suflicient tensidn on the last longloop to prevent itsbeing thrown off and yet does not unduly stretch thefirst short loops for the same reasons given in the other case.

Havin now fully described my invention what I c aim and desire toprotect by Letters Patent is: a

1. In a circular knitting machine, in combination, cylinder needles anddial needles, a knitting cam and a guard cam for the cylinder needles,loose course cams for both cylinder and dial needles, a shift cam fordepressing the guard cam, and means for actuating theiloose course andshift cams, said means being arranged to cause the shift cam to operatedirectly after the operation of the loose course cams.

needles after their depressing means hasacted, whereby drop stitches areprevented.

3. A circular kmtting machine comprising needles, a stitch cam and aguard cam, means to depress the stitch cam to cause the needles to rawlonger loops, and means to depress the guard cam to prevent the needlesrising toohigh after the first named means has acted, whereby said loopsare maintained taut enough to prevent their being thrown ofi to formdrop stitch 4. In a circular knitting machine, dial needles andcylinder. needles and a guard ,cam for the cyl a stitchcam md ne e meansfor produclnga loose course 'compnis ing a cam for depressing thestitch. am,

arm for actuating said depressing cam a cam mounted on said arm forralsmg the dial needles, another cam on said arm for the stitch and thensimilarly shifting the guard cam, while knitting, sufiiciently 'toprevent the too sudden-shortening o f the stitch.

6. A cam cylinder for knittin -g machines having .a stitch cam, a nerdcam, and a lever for lowering the stitch cam a certain distance and thenlowering the guard cam a less distance.

7. In a circular knitting machine, mean's for knitting a loose coursecomprising a movable stitch cam and an arm for depressing said stitchcam, a movable guard cam, and a cam on said arm for depressing the guardcam when the stitch cam is depressed.

In testimonyof which invention I have hereunto set my hand, atPhiladelphia, Pa., on this 14th day of September, 1921.

ROBERT W. -WA-LTON.

